Normative data for the Tower of London (Drexel version) in the Quebec-French population aged between 50 and 88 years

The Tower of London (ToL) is a neuropsychological test used to assess several executive functions such as strategical reasoning, mental planning, and problem-solving. Like other cognitive tests, performance on the ToL can vary according to age, level of education, sex, and cultural background of individuals. The present study aimed to establish normative data for the Drexel version of the ToL among French-Quebec people aged 50 years and over. The normative sample consisted of 174 healthy individuals aged 50-88 years, all from the province of Quebec, Canada. Analyses were performed to estimate the associations between age, sex, and education level on one hand, and ToL performance, on the other hand. Results indicated that Total Execution Time was associated with age, whereas the Total Type II Errors and Total Rule Violation score (Type I + II Errors) were associated with both age and education level. All other scores were not significantly associated with the demographic characteristics of the participants. Since the distributions of the data were all skewed, the normative data are presented in the form of percentile ranks. To conclude, the present norms will ease the detection of executive impairments in French-Quebec middle-aged and older adults.